The power generation efficiency of a solar cell is greatly affected by light interception due to foreign substances such as dust accumulated on a surface of the solar cell. Since such foreign substances decrease the power generation efficiency of the solar cell, it is preferable to remove them whenever they are accumulated on the surface of the solar cell. However, in the case of a large-scale solar photovoltaic power generation system, it is not efficient to clean surfaces of all solar cell panels at the same time such that they are always maintained in a clean state. This is because a cleaning apparatus for cleaning the surfaces of the solar cell panels is mechanically worn away and a great amount of energy is used up for a cleaning operation. Particularly, the degradation of the cleaning apparatus and the energy loss may become more serious in an area with great changes in a generation amount of dust depending on weather, for example, a desert area, an area affected by Asian dust, or the like.